Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Additions Charged to Expense		$ 0.5
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 3.6	3.1	$ 4.8
Reserves Acquired	0.0	0.0	0.0
Additions Charged to Expense	1.4	0.8	1.0
Deductions Credited and Write-Offs	(0.8)	(0.3)	(2.7)
Balance at End of Period	4.2	3.6	3.1
Income tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	33.6	29.7	4.1
Reserves Acquired	0.0	0.0	0.0
Additions Charged to Expense	2.4	12.3	25.6
Deductions Credited and Write-Offs	(0.2)	(8.4)
Balance at End of Period	$ 35.8	$ 33.6	$ 29.7